As an alternative to a cigarette and the like, a smoking article formed by wrapping a carbonaceous heat source chip 1, an aerosol generating material 2 such as tobacco leaves, and a mouthpiece (filter) 3 in wrapping paper 4 into a cigarette-like shape as illustrated in FIG. 9 has been suggested (see Unexamined Japanese Patent Publication No. 6-189733 for example). The smoking article is so designed that aerosol is generated from the aerosol generating material 2 by heat produced from the carbonaceous heat source chip 1, and that the aerosol is smoked through the mouthpiece 3.
In this case, the carbonaceous heat source chip 1 is obtained by mixing and kneading carbon powder serving as fuel and a combustion regulator (graphite, calcium carbonate, sodium carbonate, etc.) with binder (ammonium alginate, methyl cellulose, pectin, etc.), extruding the same to form a carbonaceous heat source rod 5, and wrapping the rod 5 in a heat insulating material 6, such as glass fiber (see Unexamined Japanese Patent Publication No. 6-7139 for example). The carbonaceous heat source rod 5 has, for example, a diameter of 3 to 5 mm. As shown in the cross section in FIG. 10, the carbonaceous heat source rod 5 has a plurality of grooves 7 axially formed on its circumferential surface. The grooves 7 function as air conduits when the aerosol generating material 2 is heated by the carbonaceous heat source rod 5, and serve to cause the carbonaceous heat source rod 5 to exhibit a desired combustion characteristic.
The carbonaceous heat source rod 5 extruded from an extrusion molding machine has moist and pliable qualities, so that it is usually guided to a heat insulating material-wrapping device by means of an air foil conveyor without crushing the grooves 7 of the carbonaceous heat source rod 5. The air foil conveyor blows out air from the bottom of the conveying path obliquely toward the downstream of the transporting direction. By so doing, the conveyor forms an air layer that prevents contact between an article and the bottom of the conveying path, and meanwhile transports the article by using the airflow.
However, even if the carbonaceous heat source rod 5 is transported to the heat insulating material-wrapping device by the air foil conveyor without crushing the carbonaceous heat source rod 5, especially the grooves 7 formed on the circumferential surface of the rod 5, the grooves 7 are occasionally crushed as illustrated in FIG. 11 when the circumferential surface of the carbonaceous heat source rod 5 is wrapped in the heat insulating material 6 by the heat insulating material-wrapping device. In such a case, there arises the problem that the desired combustion characteristic possessed by the carbonaceous heat source rod 5, namely carbonaceous heat source chip 1, cannot be retained, and the like.
In order to prevent such a problem, one idea is, for example, to dry the carbonaceous heat source rod 5 to certain hardness by using the airflow from the air foil conveyor during transportation of the air foil conveyor. The air foil conveyor, however, blows out air from the bottom of a groove forming the conveying path. Therefore, the there is the problem that the carbonaceous heat source rod 5 is greatly dried in the side of the rod 5 facing the conveying path and is not dried uniformly. Another idea is to alter the composition of the carbonaceous heat source rod 5 or to reduce the moisture content of the carbonaceous heat source rod 5 at the time of extrusion molding. However, these methods cause new problems that the extrusion molding itself becomes difficult, that the combustion characteristic and the flavor are changed, and the like.